Thermostatic control for range burners



Sept. 1, 1964 w. J. RUSSELL 5 THERMOSTATIC CONTROL FOR RANGE BURNERSFiled Feb. 27, 1962 2 Sheets-Sheet 1 w w w w H M Sept. 1, 1964 w. J.RUSSELL 3,

' THERMOSTATIC CONTROL FOR RANGE BURNERS Filed Feb. 27, 1962 2Sheets-Sheet 2 II mnmuumw...

United States Patent 3,146,945 THERMOSTATHC 0NTROL F012 RANGE BURNERSWilliam J. Russell, Malvern, Pa, assignor to Robertshaw ControlsCompany, a corporation of Delaware Filed Feb. 27, 1962, Ser. No. 175,9769 Claims. (Cl. 236-1) This invention relates to gas range burnercontrols, and deals more particularly with thermostatic regulation ofdouble throat range top burners.

The operational temperature span of domestic cooking equipmentrepresents an important characteristic Whose limits restrictadaptability of the equipment and confine the versatility of the cookingfunction. Automatic temperature control over a wide span becomesincreasingly complicated since sensitivity and uniformity of operationof the regulating equipment become difficult to maintain at alltemperature levels.

These and other difficulties encountered in automatic burner control areovercome by the present invention which effects the desired control overa wide span of temperature settings. Accordingly, it is an object of thepresent invention to thermostatically control in stages the surfaceburners of a gas range.

Another object of this invention is to obtain inherent flame to providesizing of a gas range surface burner by a single dial temperaturecontrol.

A further object of the invention is to insure stable flamecharacteristics and high cooking efiiciency.

A further object of this invention resides in the achievement of rapidand reliable burner ignition characteristics for the surface burners ofa gas range.

In practicing the present invention, pivoted means actuate a first valvemeans, which is adjustable for actuation at different positions of thepivoted means to modulate fuel flow to a range top burner at discreteflow levels. An overcenter snap mechanism actuated by the pivoted meanscontrols second valve means which efifect a distinct variation in thefuel flow intermediate the discrete levels. Temperature control meansactuate the pivoted means to maintain a predetermined set temperature atthe burner.

The exact nature of the present invention, as well as other objects andadvantages, will become apparent from the following descriptionconsidered in connection with the accompanying drawings wherein:

FIG. 1 is an end view of a control device embodying the presentinvention;

FIG. 2 is a longitudinal section of FIG. 1 with the addition of aschematic diagram of a burner control system;

FIG. 3 is a partial plan view of a detail of FIG. 2 showing anovercenter snap mechanism;

FIG. 4 is a partial section view, taken along the line 44 of FIG. 3; and

FIG. 5 is a perspective view of the overcenter snap mechanism of FIG. 2.

With reference to FIGS. 1 and 2, the control mechanism of the inventionincludes a hollow housing having an inlet tapping 12 adapted forconventional connection to a range fuel manifold (not shown), and a dial14 with graduated markings thereon conventionally constructed to bereadily removed and replaced in its correct relationship to a gas cook16. Rotation of gas cock 16 permits fuel to flow from the manifoldthrough a passage 18 and an orifice 20 into the housing cavity 22 duringthe On position of dial 14 which exists over an arc of approximately250.

A drive rod 24 is slidably connected through a pin 26 to an adjustingscrew 28 which when rotated threads Patented Sept. 1, 1964 ice itselfaxially into an adjusting nut 30. A pin 32 extends outwardly fromopposite sides of nut 30 and through aligned slots formed in acup-shaped member 34 to prevent rotation of nut 30. A bimetallic disc 36provides for ambient temperature compensation, while a cup 38, operatingin conjunction with a spring 40 compressively supported by a retainingcup 42, provides for overshoot movement as is Well known in the art. Apower element or diaphragm 44, securely attached to cup 34 as bywelding, communicates through a capillary tube 46, supported in housing10 by a tapped nut assembly 48, with a temperature sensing bulb 50centrally positioned in a burner assembly generally indicated at 52. Thepower element 44, tube 46 and temperature sensing diaphragm 44 is filledwith suitable thermostatic fiuid or charge to effect expansion andcontraction of diaphragm 44 in response to temperature variations sensedby bulb St).

A lever 54 is engaged by a hemispherical portion of adjusting nut 28 andby retaining cup 42 to be pivoted about a pin 56 by axial movement ofadjusting nut 28 in response to dial 14 or movement of diaphragm 44. Aload spring 58 compressively engaged between the nut 28 and an internalshoulder of housing 10 biases nut 28 and the associated linkage towardthe diaphragm 44. Rotation of lever 54 controls rotation of a lever 60about a pivotal axis defined by pins 62 through the action of a stud 64adjustably threaded through the free end of lever 54 for controlling theoperation of a valve-actuating overcenter snap mechanism, as will bedescribed hereinafter.

A valve carrying lever 60 has a generally inverted U-shaped crosssection, the legs of which are pivotally mounted on one end to the pins62 mounted in an internal wall of housing It) and on their opposite endcarry aligned pins 66 for pivotally mounting a second lever 68 having asimilar cross section. Spaced inwardly and downwardly from pins 66, thelegs of lever 60 are notched with V grooves 70 in which a bifurcatedsnap lever 72 is pivoted. A spring 74 is compressively engaged betweenlevers 60 and 68 and is held in place by a snap adjusting screw 76 (FIG.2) which threadedly engages lever 68 and extends through an enlargedopening 78 in lever 66. On the end opposite the pins 66, the legs oflever 68 are notched with V grooves 80 which are pivotally engaged by atoggle lever 82. A snap spring 84 is stretched across apertured portions86 and 88 on levers 72 and 82, respectively. One end of toggle lever 82is formed with extended edges 90 and 92 which alternately bear onopposite sides of snap lever 72. A valve disc 94 is pivotally mounted onthe free end of the lever 72 by means of a ball and clip assembly 96(FIG. 2). An adjustable stop screw 98 is threaded through a horizontallyextending arm 99 to engage the free end of snap lever 72 and limitcounterclockwise rotation thereof about the V grooves 70. A stud isadjustably threaded into housing lil for engagement by lever 68 toprovide a stop therefor.

Adjacent the pivot pins 66, the legs of lever 60 are formed withoppositely extending tangs 102 and 164 which threadedly carry adjustingscrews 106 and 168, respectively. Cup-shaped valve discs 110 and 112 areslidably carried on the ends of screws 166 and 168 for engagement withvalve seats 114 and 116, respectively formed in the housing 19. Thevalve discs 110 and 112 are biased towards the seats 114 and 116 by apair of coil springs 118 and 120 respectively mounted in compressionbetween the tangs 102 and 104 and a pair of clips 122 and 124 whichcarry the valve discs 110 and 112. The screws 106 and 168 extend throughenlarged openings in the clips 122 and 12.4 and have enlarged end plugs126 and 128 respectively disposed for reciprocation in the interior ofthe cup-shaped valve discs 110 and 112.

The valves 110 and 112 are sequentially operated and each of the valvesmodulates a separate gas flow from the housing cavity 22 through theircorresponding valve seats. When screws 106 and 108 are moved in anupward direction, as viewed in FIG. 4, by rotation of arm 60, the endplugs 126 and 128 engage clips 122 and 124 to lift discs 110 and 112,the process being reversed to close valve seats 114 and 116 by downwardmovement of screws 106 and 108. It will be noted that plugs 126 and 128may be adjusted to lift discs 110 and 112 at different times, and in theembodiment described herein plug 126 is adjusted lower than plug 128 toopen valve seat 114 subsequent to the opening of valve seat 116;conversely, valve seat 114 is closed prior to the closing of valve seat116.

Each of the valve seats 114- and 116 respectively open into gaspassageways 130 and 132 located within the walls of housing andcommunicating respectively with a pair of tapped outlet spuds 134 and136 on which a pair of orifices 138 and 140 are mounted. Passageway 130is intersected by a bypass passage 131 which leads to a valve seat 142engaged by the snap acting disc valve 94. Passageway 132 is alsointersected by a bypass passage 133 which directly communicates with thehousing cavity 22. The bypass flows may be adjusted by means of a flowadjusting key 144 in the bypass passageway 133 and by a similar key 146in the bypass passageway 131.

The burner 52 has an inner or simmer section which includes burner portmeans 150 fed through an annular chamber 152 by a mixing tube 154 whichcommunicates with orifice 138 as by conduit 156. An outer or mainsection of the burner 52 includes burner port means 158 in the form of aseries of ports disposed about the periphery of burner 52 and spacedbelow the simmerport means 150. The main port means 158 is fed throughan annular chamber 160 spaced radially outwardly from chamber 150 and isconnected to a mixing tube 162 which communicates with orifice 140 as byconduit 164. The inner burner port means 150 is defined by a port ring168 centrally carried by the burner 52 so as to provide a centralopening 166 through the burner.

An inclined bore 170 and a horizontal bore 172 in the burner 52 havetheir outer ends terminating in close proximity to a pilot burner 174. Aconduit 176 is connected between the pilot burner 174 and a pilot flowpassageway 178 in the housing 10 by means of a fitting 182; the pilotflow of gas from housing cavity 22 is adjustable by a flow adjusting key180 intersecting the passageway 178. With such an arrangement, ignitionis facilitated inasmuch as gas from inner chamber 152 is ignited at theouter end of bore 172 and in turn is flashed through the inclined bore170 to the inner burner port means 150.

Operation Turning dial 14 from the Off position to any desiredtemperature setting permits gas to flow from the range manifold throughgas cock 16 into the housing cavity 22 and to pilot burner 174 which canthen be ignited in any conventional manner. Drive rod 24 rotates withdial 14 and drives adjusting screw 28 axially by screwing it intoadjusting nut 30 thereby pivoting lever 54 counterclockwise about pin56. The lever 60 follows the lever 54 and pivots clockwise about thepivot pins 62. The initial movement of the valve carrying lever 60causes the end plug 128 to gradually open the modulating valve member112. The pivot pins 66 move with the lever 60 causing a clockwisemovement of the lever 68 about the pivot pins 66 due to the bias of coilspring 74. Spring 74 carries V grooves 80 in a clockwise direction whileV grooves 70 are also carried in a clockwise direction by lever 60. WhenV grooves 80 achieve a straight-line relationship with aperturedportions 86 and 88, lever 82 snaps in a clockwise direction due to theaction of spring 84 and extended edges 92 engage lever 72 therebyrotating lever 72 counterclockwise to cause seat disc 94 to snap openand permit gas flow through valve seat 142 and passageway 130 to themain section of the burner.

A significant feature of the operation of the overcenter snap mechanismdescribed is the fact that there is no lessening of force on seat disc94 as the system approaches snap point since the force angle betweenspring 84 and lever 72 does not change prior to the snapping action.This action is instantaneous, and with the force angle held constant,there is no change in the spring length. Therefore, the force on snaplever 72 remains constant until toggle lever 82 goes into snap motion.

Seat discs and 112 are arranged to be opened by clockwise rotation oflever 60 and the sequence in which they open is determined by adjustmentof screws 106 and 108 which control the distance through which plugs 126and 128 must travel before they engage clips 122 and 124 to lift discs110 and 112. With this adjustment made as herein described, seat disc112 will lift to open valve seat 116 prior to the snapping of disc 94,and disc 110 will lift subsequent to the snapping of disc 94.

Thus, it will be seen that after dial 14 is rotated to the On position,fuel will flow through valve seat 116 and passageway 132 to the simmersection of burner 52, after which valve disc 94 will snap open to permitfuel flow through seat 142 and extension 131 to the main section ofburner 52. Further rotation of lever 60 will subsequently cause valveseat 114 to open, thereby effecting increased fuel flow to the mainsection of burner 52 through passageway 130.

Temperature sensing bulb 50 which is in intimate contact with cookingutensils placed on burner 52 responds to temperature increases bycausing diaphragm 44 to expand due to expansion of the thermal chargingmedium. As the contents of the utensil approach the temperature to whichdial 14 has been set, expansion of diaphragm 44 effects clockwiserotation of lever 54, thereby rotating lever 60 counterclockwise, firstclosing valve seat 114 and cutting off fuel flow therethrough to themain section of burner 52. Disc 94 snaps shut following the closing ofvalve seat 114 when continued counterclockwise rotation of lever 60causes lever 68 to engage stud 100, thereby rotating lever 68counterclockwise about pins 66 to effect alignment of V grooves 80 withapertured portions 86 and 88. Then toggle lever 82 snapscounterclockwise, snap lever 72 being rotated in a clockwise directionby engagement therewith of extended edges 90.

Valve seat 116 closes last due to continued rotation of lever 60, and atthis point the only fuel flowing to burner 52 will be through adjustingkey 144 and bypass extension 133. Decrease in the temperature of thecontents of the cooking utensil, as by the addition of cold food, water,etc., causes contraction of diaphragm 44 and counterclockwise rotationof lever 54, thereby reinitiating the' valve opening procedurepreviously described to a degree sufiicient to bring the contents of theutensil to the set temperature.

With the contents at set temperature, the simmer section of burner 52will continue receiving fuel at a rate controlled by adjustment of key144, which may be in the range of 200 B.t.u. per hour. The flame may bemodulated from a rate of 200 B.t.u. per hour to approximately 1000B.t.u. by the action of valve seat and disc 112, 116. From 1000 B.t.u.fuel input is snapped to 2000 B.t.u. (1000 B.t.u. on the main section ofthe burner) by the action of the overcenter snap mechanism and valveseat disc 94, 142. Operation of valve seat disc 110, 114 may be adaptedto modulate to a full fuel input of over 12000 B.t.u. per hour whichwould be a minimal capability for bringing large loads to temperaturewith adequate speed.

Thus, there is provided the capability for performance of cookingoperations over an entire wide span of temperatures normally required ofrange top burners. This span may be divided into three basic categories:the warming range which exists between F. to F.; the

keep-warm or simmer-thru-boiling range from approximately 150 F. toslightly above 212 F.; and the frying range which would encompasstemperatures from approximately 275 F. to 400 F.

The actual heat output at each desired temperature will vary inaccordance with load and the 12000 B.t.u. re quired to bring loadsquickly to temperature is therefore drastically reduced, after a timedependent on load size, once the desired temperature has been reached.Moreover, at each temperature level required, heat input will beautomatically regulated to maintain the set temperature and toreestablish that temperature in the event that varying conditions causeit to change. Due to its flexibility with regard to levels of heatinput, the present invention is able to maintain set temperature over awide range with uniform sensitivity and accuracy at each temperaturelevel.

Another significant advantage of this invention arises as a result ofmaking the simmer or inner section capacity larger than conventionalburners while maintaining small physical size and reduced capacity inthe main section with normal port openings. The smaller physical size ofthe main section and reduced port ring diameter permits a smaller flamepattern from the main port ring, which combined with the larger innersection flame pattern attains more efiicient heat transfer to thecooking utensil.

An additional advantage arising from utilization of a dual throat burneris the ability to achieve improved flame pattern with respect to pansize as opposed to a single burner of large capacity. The averagetemperature controlled top burner of 12000 B.t.u. capacity requiresapproximately 1200 B.t.u. for stable flame characteristics, therebymaking low temperatures diflicult to obtain and then only by sacrificingflame stability. The present novel combination, however, permits stableoperation at an input as low as 200 Btu. per hour, thereby providingcontrolled temperatures with stability over an enlarged span. Thisfeature combined with automatic control results in higher efiiciency,improved ignition and stable flame characteristics, and elimination ofthe need for flame setting devices, thus attaining truly automaticperformance.

While in the foregoing there has been disclosed a specific embodiment ofthe invention, it will be apparent that many modifications andvariations thereof are possible. It should, therefore, be understoodthat all matter contained in the foregoing description and shown on thedrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

1. In a control system for a gas range, the combination comprising asurface burner having a spaced pair of burner port means, firstmodulating valve means regulating a gas flow to one of said port means,snap acting valve means controlling an additional gas flow to said oneport means, second modulating valve means regulating a gas flow to theother of said port means, thermally responsive means including meansmovable in response to temperature variations sensed at said burner, andvalve actuating means operatively connected to said movable means and tosaid first and second modulating valve means and said snap acting valvemeans.

2. The combination as recited in claim 1 wherein bypass means supplies abypass gas flow to said other port means to maintain a minimum flame atsaid surface burner.

3. The combination as recited in claim 2 wherein said one burner portmeans comprises a series of annularly spaced ports and said other burnerport means is spaced inwardly and upwardly from said annularly spacedports.

4. The combination as recited in claim 3 wherein a manually operablevalve means is positioned upstream of said bypass means, said first andsecond modulating valve means and said snap acting valve means.

5. In a thermostatic control device, the combination comprising ahousing having an inlet for receiving a fluid flow and a pair ofoutlets, a pair of spaced valve seats in said housing communicating withsaid pair of outlets, valve carrying means disposed in said housing formovement between a plurality of positions, modulating valve means onsaid valve carrying means cooperating with said pair of spaced valveseats to modulate fluid flow to said outlets, said modulating valvemeans including a first valve member movable into engagement with one ofsaid valve seats when said carrying means is in one position and asecond valve member movable into engagement with the other of said valveseats when said carrying means is in another position, snap acting valvemeans operatively connected to said carrying means for controlling anadditional fluid flow to one of said outlets, and being actuated whensaid carrying means is in a position intermediate its said one andanother position, and thermally responsive means operatively connectedto said carrying means for imparting a regulatory movement thereto inresponse to temperature variations.

6. In a thermostatic control device, the combination comprising ahousing having an inlet and first and second outlets, control valvemeans operably disposed in said housing adjacent said inlet forcontrolling a fluid flow into said housing, thermally responsive meansincluding a movable element having a regulatory movement in response totemperature variations, a valve actuating lever pivoted in said housingfor movement between first and second actuating positions, a first valvemeans for modulating a fluid flow to said first outlet, a second valvemeans for modulating a fluid flowto said second outlet, said first andsecond valve means being sequentially operated by said valve actuatinglever, a third valve means for controlling an additional fluid flow tosaid second outlet, a snap acting mechanism operatively connectedbetween said valve actuating lever and said third valve means andincluding iovercenter means actuated at an intermediate position betweenthe first and second actuating positions of said valve actuating leverwhereby said third valve means is actuated with a snap action betweenthe sequential operations of said first and second valve means, and anoperating lever pivotally mounted in said housing in engagement withsaid valve actuating lever and said movable element of said thermallyresponsive means whereby said first, second and third valve means areoperated in response to temperature variations.

7. The combination as recited in claim 6' wherein said snap actingmechanism includes a snap lever having one end pivotally engaging saidvalve actuating lever and an opposite end carrying a valve element ofsaid third valve means, and pivotal lever means having one end pivotallycarried by said valve actuating lever for movement thereby and anopposite end formed with V grooves, and wherein said overcenter meanscomprises a toggle link having one end pivotally mounted in said Vgrooves and an opposite end alternately engaging said snap lever, and acoil spring mounted in tension between said toggle link and said snaplever.

8. In a thermostatic control device for supplying fuel flow to gas rangesurface burner means having a simmer burner, a main burner and a pilotburner, the combination comprising a housing having an inlet and a valvechamber, control valve means operably disposed in said housing adjacentsaid inlet for controlling a fluid flow into said chamber, a pilot flowoutlet from said chamber adapted to supply a pilot fluid flow to thepilot burner whenever said control valve means is in an operativeposition, a simmer flow outlet from said chamber adapted to supply asimmer fluid flow to the simmer burner whereby a minimum flame maintainsthe surface burner means at a minimum level of heat output, firstmodulating valve means in said chamber regulating a second simmer fluidflow to said simmer flow outlet whereby an increased simmer flame variesthe surface burner means heat output between the minimum level and asecond level in response to modulation, a main flow outlet from saidchamber adapted to supply a main fluid flow to the main burner, snapacting valve means in said chamber controlling a main fluid flow to saidmain flow outlet whereby a constant flame at the main burner increasesthe surface burner means heat output to .a third level, secondmodulating valve means in said chamber regulating a second main fluidflow to said main flow outlet whereby an increased main flame varies thesurface burner means heat output between the third level and a maximumlevel in response to modulation, a valve actuating lever pivotallymounted in said chamber for movement between first, intermediate andsecond actuating positions, said lever actuating said first and secondmodulating valve means when disposed in its first and second actuatingpositions, respectively, and actuating said snap acting valve means whendisposed in its intermediate position, a levered operator pivotallymounted in said chamber in operative enagement with said valve actuatinglever, an operative connection between said control valve means and saidoperator whereby movement of said control valve means causes sequentialactuation of said first modulating valve means, said snap acting valvemeans and said second modulating valve means, thermally responsive meansoperable in response to temperature variations at the surface burnermeans, and an operative connection between said thermal- 1y responsivemeans and said operator causing sequential actuation of said secondmodulating valve means, said snap acting valve means and said firstmodulating means in accordance with a decreasing heat demand at thesurface burner means.

9. A thermostatic device for regulating temperature at a burnercomprising valve means adapted to control fuel flow to the burner, saidvalve means including a pair of valve seats and a cooperating pair ofmovable valve elements, pivoted means carrying said pair of movablevalve elements in staggered relationship and sequentially actuating saidpair of movable valve elements to modulate fuel flow to the burner, snapvalve means actuated in accordance with movement of said pivoted meansfor effecting an additional fuel flow to the burner, and temperaturecontrol means actuating said pivoted means to maintain a predeterminedtemperature at the burner.

References Cited in the file of this patent UNITED STATES PATENTS2,121,977 Newell June 28, 1938 2,719,673 McCarty et al. Oct. 4, 19552,807,423 Eskin Sept. 24, 1957 2,950,865 Lamar Aug. 30, 1960

9. A THERMOSTATIC DEVICE FOR REGULATING TEMPERATURE AT A BURNERCOMPRISING VALVE MEANS ADAPTED TO CONTROL FUEL FLOW TO THE BURNER, SAIDVALVE MEANS INCLUDING A PAIR OF VALVE SEATS AND A COOPERATING PAIR OFMOVABLE VALVE ELEMENTS, PIVOTED MEANS CARRYING SAID PAIR OF MOVABLEVALVE ELEMENTS IN STAGGERED RELATIONSHIP AND SEQUENTIALLY ACTUATING SAIDPAIR OF MOVABLE VALVE ELEMENTS TO MODULATE FUEL FLOW TO THE BURNER, SNAPVALVE MEANS ACTUATED IN AC-